Interaction chambers typically operate by flowing fluid from one or more inlet cylinders, through one or more microchannels, and out one or more outlet cylinders. The transition of the fluid flow into the microchannels can lead to cavitation, a physical phenomenon of formation of vapor cavities (bubbles) inside a liquid. Cavitation is the consequence of rapid changes in pressure. When pressure drops below a vaporization pressure, liquid boils and forms vapor bubbles.
There are several disadvantages associated with cavitation inside a microchannel. First, the cavities can implode as the fluid pressure recovers downstream and can generate an intense shockwave. This can cause significant damage to the internal surface of the interaction chamber and downstream piping (e.g., the wear of the components that greatly reduces chamber performance and life). Cavitation can also introduce local high temperature spots, causing damage to certain heat sensitive materials. Second, since the formed cavities stay and occupy a certain volume inside the microchannel, the flow through the microchannel can be blocked and plugging issues can occur when processing certain solid dispersions or materials with high aspect ratios. Third, with the reduced available cross-sectional area near the microchannel entrance, the place with the most severe cavitation, the flow rate is limited and subsequently results in a lower average flow velocity at the channel exit. This can reduce the energy of the fluid at the micro channel exit and lead to the reduction of process efficiency for certain applications.